韧带损伤影响腰椎稳定性的生物力学特征

Biomechanical characteristics of ligament injury affecting lumbar spine stability

背景:韧带是维持腰椎稳定的重要结构,由于产生的机械应力这些结构容易退化,而对于韧带损伤的研究较少。目的:基于三维有限元模型模拟韧带损伤,确定各个韧带在运动状态下的活动度及应力方面的作用,系统探讨韧带受损对腰椎稳定性的影响和生物力学意义。方法:建立腰椎L4-L5有限元模型,约束L5下表面所有自由度,施加5 N·m力矩模拟腰椎的各个运动状态,通过改变韧带弹性模量模拟韧带渐进式受损。结果与结论:①大部分韧带损伤伸展活动度都出现了明显的增大;相比之下侧弯活动度无明显变化。②关节囊韧带受损后前屈、后伸和侧弯的活动度明显增大;前纵韧带受损后伸展活动度明显增大;横突韧带损伤导致侧弯活动度明显增大。③单韧带损伤后,伸展时活动度变化最为显著;单韧带受损后剩余韧带应力增大,尤其是关节囊韧带;整体来看棘间韧带和黄韧带应力变化最不明显;韧带应力在侧弯状态下变化最小,而扭转状态下变化最大。④韧带受损并未导致椎间盘压力发生重大变化,提示韧带损伤导致腰椎活动度增大,影响腰椎稳定性。⑤关节囊韧带稳定前屈、后伸和侧弯;前纵韧带稳定后伸;横突韧带稳定侧弯。⑥后伸运动对韧带损伤敏感,可通过后伸运动检查韧带病理变化。⑦单韧带损伤后剩余韧带给予应力补偿以维持腰椎稳定性。⑧棘间韧带和黄韧带损伤对周围韧带影响最小,关节囊韧带损伤对周围韧带影响最大。⑨韧带损伤对侧弯运动下的剩余韧带应力影响最小,而对扭转运动下的韧带应力影响最大,韧带损伤患者应避免扭转运动;韧带损伤不影响椎间盘压力。

BACKGROUND:Ligaments are important structures in maintaining the stability of the lumbar spine,and these structures are prone to degradation due to the generated mechanical stress.However,there are few studies on ligament injuries.OBJECTIVE:To determine the range of motion and stress of each ligament in the state of motion based on a three-dimensional finite element model,and to systematically explore the influence of ligament injury on the stability of the lumbar spine and its biomechanical significance.METHODS:The L4-L5 lumbar finite element model was established.All free forces on the lower surface of L5 were constrained,and a torque of 5 N·m was applied to simulate the motion states of the lumbar spine.Progressive ligament damage was simulated by changing Young’s modulus of the ligament.RESULTS AND CONCLUSION:(1)The extension range of motion of most ligament injuries increased significantly.In contrast,there was no significant change in the lateral bending range of motion.(2)The range of motion of capsular ligament injury increased significantly in flexion,extension and lateral bending.The extension range of motion increased significantly after the anterior longitudinal ligament injury.Intertransverse ligament injury resulted in a significant increase in the lateral bending range of motion.(3)After a single ligament injury,the most significant change in range of motion was observed during extension.After a single ligament injury,the stress of the remaining ligaments increased,especially the capsular ligament.The stress changes of the interspinous ligament and ligamentum flavum were the least obvious.Ligament stress changes least in lateral bending and most in torsion.(4)Ligament damage did not result in major changes in disc pressure,indicating that ligament injury leads to an increased range of motion of the lumbar spine and affects the stability of the lumbar spine.(5)Capsular ligament was stable in flexion,extension and lateral bending.The anterior longitudinal ligament showed a stable extension;the intertransverse ligament stabilizes the lateral curve.(6)Extension exercise is sensitive to a ligament injury,and the pathological changes of the ligament can be examined by extension exercise.(7)Stress compensation was given to the remaining ligaments to maintain the stability of the lumbar spine after a single ligament injury.(8)Interspinous ligament and ligamentum flavum injuries have the least impact on the peripheral ligaments,while capsular ligament injuries have the greatest impact on the peripheral ligaments.(9)The ligament injury has the least effect on the residual ligament stress during lateral bending exercise,while it has the greatest effect on the ligament stress during the twisting exercise.Patients with ligament injury should avoid twisting exercises.Ligament injuries do not affect disc pressure.